There are several tomato diseases which are common in our area. Two of these cause spots on the plant leaves, usually beginning on the lower leaves, and progressing upward. The spotted leaves turn yellow, then brown and drop off.

Both of these diseases, early blight and Septoria leaf spot are more serious in damp, rainy weather. Poor watering practices can lead to an outbreak of tomato leaf disease. Both diseases can cause severe loss of leaves, which in turn can lead to sunscald of the fruits.

Early blight and Septoria can be controlled by removal of old tomato vines in the fall and by regular spraying with a fungicide. Spraying should begin at the first sign of the disease on the lower leaves and repeated every 7-10 days as needed. Fungicides to use should include Chlorothalonil. Be sure to use a sprayer that has not been used for a weed killer such as 2,4-D. Tomatoes are very easily damaged by 2-4,D, and this chemical is difficult to completely remove from a sprayer.

Another tomato leaf disorder seen in our area is leaf roll. The leaves of the plant roll upward and have a leathery texture. This may be caused by excess moisture, staking and pruning plants, heavy applications of nitrogen, and root damage from close cultivation. Leaf roll is not contagious, and usually doesn't have much of an effect on growth of fruit yield.

Herbicide damage is another leaf problem. This results from using 2,4-D or related weed killers too close to tomatoes. Leaves of affected plants often become narrow, twisted and distorted. Stems may split and fruits may develop a catface pattern on them. Plants exposed to small amounts of 2,4-D usually recover, particularly if growing conditions are good.

This page was last updated May 2003

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